This invention relates generally to a process for making polymer plates and more specifically to a unique process for continuously manufacturing polymer plates having a layer of resin composition that is soluble in water and/or a volatile solvent and is useful, for example, as a photopolymerizable element for a printing plate.
A significant demand has developed in the printing and newspaper industries for photopolymer printing plates, sometimes referred to as cladplates, which include a supporting structure, such as metal, and a photopolymerizable resin composition rigidly secured to the supporting structure. Conventional techniques for making such plates involve the molding, casting, extrusion and/or calendering of the resin composition onto a support structure, such as aluminum, tin or steel. It is known, for example, that resin compositions, having a water soluble or volatile solvent soluble polymer and a monomer compatible therewith as their primary components, can first be molded to form a plate or membrane, and then subsequently adhered onto a base or support plate, such as aluminum, tin or steel plates.
Besides requiring two distinct and, therefore, expensive steps, e.g., molding and then adhering, such techniques are not entirely satisfactory for use with the most desirable types of resin compositions useful as photopolymerizable elements. It has been recognized, for example, that the most desirable types of resin compositions include highly reactive monomer components that are stimulated at temperatures of 80.degree.C or more and, thus, generally cause the resin composition to assume a gelatin condition at commonly used molding temperatures. Conventional molding techniques, therefore, had to be modified to operate at temperatures below 80.degree.C.
In addition, however, when the most desirable types of resin compositions are exposed to air at temperatures above 40.degree.C, their surfaces begin to dry and an undesirable skin is formed on the resin. Thus, conventional molding techniques have the further disadvantage of permitting such air exposure and skin formation on the resin compositions.
Finally, it has also been recognized that the monomer component of such desired resin compositions shifts at temperatures below 20.degree.C and such shifts reduce the adhesion strength of the surface of such resin compositions to the base or support material.
Thus, there is a significant need for polymer plates utilizing such desired resin compositions and for a process for making such plates without the above-mentioned disadvantages of conventional molding techniques.